1. Field of the Invention
The invention relates to a referencing device for mapping the position of bodily surgical or examination target points comprising at least three reflectors, the position of which can be localized by a computer-assisted position tracking and/or a CT scan, and an adapter connected to the reflectors, by means of which the referencing device is attachable to a part of the body, wherein said adapter comprises a mouthpiece securable to said upper jaw by means of vacuum pressure.
The invention relates furthermore to a method for referencing bodily surgical or examination target points. The device in accordance with the invention is employed in radiotherapy and neurosurgery.
2. Description of the Prior Art
Referencing devices which make visible the current position of the patent as well as the three-dimensional position of surgical instruments and hardware on a computer monitor or which contribute towards directly mapping positions in radiosurgery are known. They serve to reference the anatomical data obtained for example by a CT scan in a fiducial system, i.e. permitting three-dimensional assignment of the patient anatomy to the referencing device in each case which in turn can be tracked by a position tracking system for monitoring in the operating room. Position tracking systems of this kind comprise for example an infrared emitter and two infrared cameras which "see" the three-dimensional position of reflectors attached to the patient or to the surgical instruments and hardware. In this arrangement a computer assigned to the position tracking facility computes from the information on the reflector position the up-dated or current position of the patient as well as that of the surgical instruments and hardware and assigns this information to the patient data from the CT scan thus making image-assisted navigation in the operating room or computer-assisted radiotherapy possible.
To enable the anatomy of the patient as established from the CT scan in the above systems to be mapped as precisely as possible artifical landmarks are attached to the patient prior to scanning, the images of which are mapped in the CT. In actual surgery the positions of such landmarks are tracked by a position tracking system as described above, for instance, and thus due to the fixed assignment of the patient anatomy to the position of the landmarks the current position of the surgery target points is also known via the known position of the landmarks.
The landmarks can be principally attached to the patient invasively or non-invasively. Invasive methods of attachment, for example, trephining and securing the landmarks in the holes are highly accurate but extremely stress the patient. Noninvasive methods involve, for example, attaching the landmarks to the skin by means of surgical plaster. The drawback here is that the skin is prone to being slightly shifted which in a worst case condition may amount to a few centimeters resulting in position tracking with such bonded landmarks being inaccurate.
Known from German Patent 19 619 761 A1 is a locating device for the human head in which an upper jaw impression mold is applied to the patient which can be affixed to the upper jaw by vacuum pressure. Applying this upper jaw impression mold in the mouth of the patient merely serves to precisely locate the head of the patient; however, the upper jaw impression mold for locating the head is totally rigid and unmovable in use.